The NHLBI Electron Microscopy Core Facility has supported projects using the following techniques in the past year: 1. Fixation, embedding, ultra-thin sectioning and transmission EM digital imaging of tissues and cells. 2. EM immunocytochemistry, including immunogold localization of proteins and other antigens within and on the surface of cells by pre-embedding and cryo-immunogold techniques. 3. Negative staining of large proteins, polymers and supramolecular structures as well as lipid and membrane vesicles for transmission EM imaging as well as platinum shadowing of large molecules. 4. Fixation, critical point drying, sputter-coating and scanning EM digital imaging of small organisms, organs, tissues and cells, as well as other materials such as artificial matrices. 5. Platinum carbon replicas of extracted, critical point dried cytoskeletons and the substrate-attached membranes of cultured cells In the past year, we have supported 25 projects for 18 principal investigators in the NHLBI/DIR and 1 project for a scientist outside the DIR. We have trained 10 postdoctoral fellows, students and contractors in the use of the scanning and transmission electron microscopes.